2.8 / 125mm material specially for Radozhiva prepared Rodion Eshmakov (subscribe to Instagram!)
The lens received a new look during adaptation - the retaining ring and part of the body part remained from the old one. increase.
As in the USSR, East Germany produced a large number of low-volume optics intended for special applications. In the vastness of the CIS, it is less common than the Soviet one, and therefore is less studied in the circle of amateur photographers. This article focuses on a rare unnamed 125 / 2.8 lens made by Pentacon, which, according to the previous owner, was part of a research instrument from an unnamed institute of the Russian Academy of Sciences in Moscow.
Specifications:
Optical design - 5 elements in 3 groups, "Sonnar";
Pentacon 125 / 2.8 is made according to the same scheme as the famous CZJ Sonnar 180 / 2.8
Focal length - 125 mm; (not 135 like the mass Pentacon 135 / 2.8 https://radojuva.com/2013/10/pentacon-2-8-135-pre-set-black/
Aperture ratio - 1: 2.8;
Coating circle diameter - ~ 50 mm;
Diaphragm - not provided by the design;
Body material - copper, aluminum;
Mount to the camera - М28 × 0.75.
Design and adaptation features
I had a very hard time with this specimen: the lens was apparently kept in a damp room, which caused mushrooms to settle in it and all the threads were completely acidified. Greetings from the Department of Electrochemistry to the designers who allowed the simultaneous coexistence of copper and aluminum parts in the lens. Outwardly, at first glance, he did not look so bad. In design, it resembled Pentacon optics for movie cameras, for example - a pancratic lens. Pentovar-16.
Despite the presence of a focusing mechanism and a generally pleasant appearance, the lens barrel was completely unsuitable for setting the aperture. The thing is that the lens unit turned out to be at the same time a part of the focusing mechanism, and also the fact that the lens could not be disassembled without the use of the brute force of the cut-off wheels. In general, its disassembly and maintenance became an extremely non-trivial task and the body parts suffered greatly.
I managed to completely remove the mushroom from the lens optics (the main localization is the rear lens), but of course, traces on the anti-reflection coating remained - this further reduced the contrast of the image obtained by the lens.
For adaptation, a set of parts was made to order, which made it possible to place the lens optics in a lens unit with a lens diaphragm (otherwise it would be difficult to maintain exact lens distances) and a focusing mechanism with a hard-stop MDF.
The aperture is adjusted by rotating the nose, and the current aperture value is indicated in the window.
Due to the small rear focal length, the lens was made for an EF mount.
A luxurious lens diaphragm is visible from the shank side.
During the adaptation, it was possible to leave one of the body parts, which also served to implement the MDF hard stop. Despite the severe damage sustained during disassembly and rework, the serial number of the lens can still be read from it.
Most importantly, the factory logo and lens parameters are no longer readable. But the serial number is still visible.
Optics Pentacon 125 / 2.8 has a single-layer coating of blue-cyan shades. A similar one is used on optics designed to work with long-wavelength radiation. The lumen of the lens turns yellow.
Blue color coating reflects blue rays - the lens turns yellow.
The multi-blade diaphragm always leaves the pupil of the lens round.
Thus, the lens in full-fledged adaptation turned out to be not easy - with it there are no less worries than with the alteration of projection aplanates. However, the design can be greatly simplified by abandoning the preservation of the native body parts and design elements. If there is no need for a diaphragm, the alteration is trivial and is reduced to the groove of the standard shank for the M42 thread.
Despite all the difficulties that arose, the lens not only received all the necessary controls, but also an original appearance.
Optical properties
The lens has excellent image quality in the center of the frame from open aperture with slight spherical aberration and purplish green chromaticity visible. The lens is very bad at F / 2.8 at the edge of the 36x24 mm frame - most likely, it is corrected within a smaller field (~ APC-C). This is also evidenced by the factory mount to the camera with an inner diameter of ~ 25 mm.
The aperture set in the lens position does not quite correctly perform its function with this lens - limiting the pupil to F / 5.6 and further introduces a noticeable vignetting in the full frame. At open aperture, the lens works well with the shift adapter on a full frame. The magnitude of aberrations during aperture decreases both in the center and along the edge of the frame - spherochromatism disappears, coma decreases. A high-quality image can only be obtained within the APS-C frame due to the high value of field chromatism and other aberrations.
Image contrast is surprisingly good in soft lighting, although a thick veil appears in the backlight. Most likely, the lens handled light better without damage. Blue enlightenment produces interesting highlights from point light sources that are somewhat reminiscent of those of modern cinema lenses. Zeiss Supreme Prime Radiance... Isn't it T-Blue?)
The residual aberration profile of this lens is quite unusual, which seems to be related to the scope of application. In other words, the character of the picture does not look like the picture of the CZJ Sonnar 180 / 2.8, as one might expect. The bokeh is quite soft, especially at close focusing distances or without the use of a shift adapter, when the effect of field aberrations is small.
Below are sample photos taken with the Sony A7s full-frame camera. Some of the photos were taken using the Fotodiox shift adapter (the principle of operation is described here).
Sample photos for this lens and Canon EOS 5D from Oleg Isaev (his Instagram):
Conclusions
When purchasing technical optics, you never know for sure what you will get. The hard work on this lens was a challenge for me. Despite the imperfect condition, the Pentacon 125 / 2.8 turned out to be a fairly good lens in terms of the totality of its properties, which can be considered as "Jupiter-37 at maximum" or "Tair-11, but sharper." At the same time, there is a huge number of more affordable, interesting and / or high-quality optics of the 135 / 2.8 class.
You will find more reviews from readers of Radozhiva here... All Rodion reviews in one place here.
Unusually, the portraits of him in black and white are better, perhaps, or in "retro" processing. I believe that the purpose of such work is primarily in the process: the lens is successfully placed on the camera and performs its function, but how it does it is also important, but this is secondary. I see that the second model photographer also has a lens-alteration, and the camera is excellent, because I have the same one)
The second one has my own 35KP 75 / 1.8 lens, the review of which is on the website. By the way, it, like this 125 / 2.8 and some other lenses, can be purchased from me.
Can you tell me about the price? Interested in 2.8 / 125
Write to mail (rudzil@yandex.ru) or inst. The price seems to be $ 90.
I always wondered - why? Well, except for the challenge?
cuddling is the name of this phenomenon.
“'Cause I Can”
Nikkor 105 / 2.5 pre-AI - good glass? And what about the Sonnar 180 / 2.8? So this lens was of interest to me as something unknown, special. When I found out the optical scheme, I definitely decided to adapt it. I am not disappointed with the result - the lens is at least more interesting than Jupiters and sharper than Tairov. The highlight in the picture is available. The proportionality of effort and result is a secondary issue when it comes to the only known specimen at the time of adaptation. In general, the Lance Club now has information about the second, which, apparently, was refined into the M42 without changing the design.
👍
So and not the mind of NAVISCHO and the price? What if you want to be so busy?
Don't get overwhelmed. Do not mind, well, God from him.
Rodion, what will you screw to the camera when you try all the lenses in the world?
Invents his own.
Handsome men. Very interesting. Thanks. :)